A patient on isoniazid for latent TB prophylaxis develops bilateral numbness and tingling in the feet. Laboratory testing reveals decreased pyridoxal phosphate levels. Which supplementation prevents this adverse effect without reducing isoniazid efficacy?
- A Vitamin B1 (Thiamine)
- B Vitamin B12 (Cobalamin)
- C Vitamin B6 (Pyridoxine) ✓
- D Folic acid
Correct answer: C. Vitamin B6 (Pyridoxine)
Explanation
Isoniazid structurally resembles pyridoxine (C6) and increases its renal excretion, causing pyridoxine deficiency. This impairs GABA synthesis, producing peripheral neuropathy. Low-dose pyridoxine (10-25 mg/day) prevents neuropathy without antagonizing isoniazid efficacy. High doses may theoretically reduce INH activity, but prophylactic doses do not.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.